The Therma Tech line is made from hot dipped galvanized wood grain textured steel skins that are embossed with one of four panel designs then sandwiched with a (EPS) polystyrene core. This type of construction forms a true thermal barrier between front and back of door. 20 gauge steel backer plates are toggle locked to the inside of the back skin prior to assembly. Exterior skins are secured to a (EPS) polystyrene core with Urethane adhesive, a method of construction that is unparalleled in strength. Four series: (1) Therma Tech™ (2) Therma Tech II™ (3)Therma Max™ (4) Tri Tech™